This invention pertains to the art of energy absorbers and, more particularly, to energy absorbers using a deformable torsion member.
The invention is particularly applicable to a vehicle seat construction and will be described with particular reference to a plastic school bus seat. However, it will be appreciated that the invention has broader applications and may be adapted to use in other applications. Such applications may include, for example, an energy absorber for an automobile bumper, a torsional spring designed to decelerate rail cars, and the like.
In the past, school bus seats were conventionally constructed of bulky steel frames welded together at various strategic locations. With the steel frame designs, a great amount of padding is required on both the seat front and rear portions to meet modern crash standards. This results in a generally thick seat back member which, in turn, requires an excessive amount of interior bus space, particularly when considered in light of the total number of seats provided in a bus. The conventional padded steel frames also add a great deal of weight to the vehicles, thus reducing the efficiency and raising the cost of vehicle operation.
Federal Motor Vehicle Safety Standard No. 222 establishes specific capabilities which must be met by school bus passenger seating. For example, seat back deflection shall not exceed 14 inches, and the seats must be capable of absorbing over 16,000 in.-lbs. of energy in the forward direction. Furthermore, seat back deflection shall not exceed 10 inches in the rearward direction, and required head and knee form standards must also be met. Because of these stringent requirements, alternative school bus seats have not been widely developed beyond the above-noted conventional steel frame constructions.
It has been considered desirable, therefore, to develop an alternative seat arrangement which would meet federal safety standards and provide more efficient utilization of the available space in the interior of a bus. Such alternative seat arrangement should cost no more than the conventional seat constructions. The subject invention is believed to meet the foregoing needs and others, and provide an energy absorber which is simple to manufacture, effective in use, compact, and readily adapted to use in a wide variety of different applications.